If you chose (f), you’re like most people who think raindrops are shaped like tears.

If you chose (e), you’re probably just hungry.

In either case you’re wrong.

That leaves us with lunch. Let’s start from the top.

Choice (a), orange, is a sphere. Water droplets are spherical because water is cohesive, meaning it sticks to itself. The “skin” that holds the drop together is surface tension and the reason insects can walk on water.

If you chose (a), you made a logical choice based on the properties of water, but you are wrong. Notice that you were not asked to identify the shape of a raindrop sitting on a leaf. You were asked to identify the shape of a falling raindrop. (Always read questions carefully!)

Moving down the list to (b), we encounter the potato chip. Potato chips come in many shapes, ranging from relatively flat to completely crumpled. Have you ever seen a raindrop that looks even a little bit like a potato chip? If you chose (b) you are wrong, but have a good sense of humor.

Choice (c), hot dog, is an interesting option. Could a spherical drop of water morph into the cylindrical shape of a hot dog? After all, a hot dog is a cylinder with a hemisphere (half sphere) on each end. Could a water droplet in free fall separate itself into two hemispheres with a long drip of water in between? Although this is an imaginative idea, the laws of physics make it impossible.

Choice (d), hamburger bun, is the only remaining choice, and is the correct answer. Here’s why:

A raindrop is acted upon by three forces: gravity, buoyancy, and drag. Gravity is the force that pulls the drop toward the earth, while buoyancy of the surrounding air pushes it upward and keeps it from falling. When the force of gravity is greater than the force of buoyancy, the raindrop falls. The air around it creates drag, slowing the drop down to its maximum speed. In the process, the sphere is distorted into a shape that resembles a hamburger bun.

Air pressure at the bottom of the falling drop is greater than at the top. (Image courtesy of NASA)

Bugs bite, drink blood, and rob food from gardens and fields. They can even kill plants, animals, and, occasionally, people. Is bugging a crime? In her latest book, Bug Shots, Alexandra Siy compiles "rap sheets" on several of the major categories of bugs and takes a very close look at some of the types of insects in an engaging text. For more information, clickhere. Alex Siy is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

No one wants to mess with someone who is super strong! Even if you’re undersized, especially if you’re undersized, you’ve got to try the two tricks in this Minute .

Here’s the first challenge: Bet another person can’t remove your hand from the top of your head. The challenge-taker must try to remove your hand according to your rules. Otherwise, it’s cheating. Sit on the floor. Place your hand with your fingers spread apart firmly on the top of your head. Have your friend grasp your lower arm next to your elbow. Now let him/her pull upward, trying to lift your hand from the top of your head.

Chances are excellent that you’ll be lifted off the ground before your palm parts from its perch.

Why is this so? If you’ve studied simple machines you may have learned about a mechanical advantage. That’s how a simple machine such as a lever can multiply your strength or speed. In this case, you’re putting your friend at a mechanical disadvantage. Your arm is a lever. In order to move your hand from the top of your head, you need an upward force near your hand. If that force is delivered as far away from your hand as possible, it loses its power. It’s easy to remove your hand if you deliver an upward force near your wrist. But at your elbow? No way! Got it?

Here’s another trick with the secret sauce of physics. Bet you can keep ten people from shoving you into a wall. Place your hands against a wall with your fingers spread and your arms outstretched. Have ten people line up behind you, hands on the shoulders of the person in front of them. At the count of three, have everyone push on the person in front of them as hard as they can. I mean, really lean in.

You, hero of the day, can hold them all off and not bend your elbows.

Why? Actually, each person absorbs the force of the person behind them so that you are not experiencing the cumulative force of ten people, only the force of the person directly behind you. So pick someone smaller than you to be that first person. If you’re not super strong, you can still be super smart.

If you don’t want to try this yourself, look at my videos of other people doing the challenges. Maybe you’ll change your mind.

If you like these bets, check out Vicki Cobb’s new release of We Dare You! You might want to join her We Dare You! National Video Project and make more videos yourself from her book. Learn more about it here.

Vicki Cobb is a member of iNK’s Authors on Call. You can invite her to your class through the magic of videoconferencing. Learn more about it here.

When you think of the Olympics you think of the sports: Speed skating, Bobsled. Snowboarding. Track, Gymnastics. Swimming. Tennis. Just to name a few.

You may even think about some of the Olympians: Snowboarders Shaun White and Kelly Clark. Speed skater Apollo Ohno. Swimmers Michael Phelps and Katie Ledecky. Or even gymnast Simone Biles and sprinter Usain Bolt.

But do you ever think about the science behind each sport? You should. Math and physics play a huge part in every part in the Olympics. Think about it. One of the most basic forces, friction, is a factor in everything an athlete does. What is friction? It’s the force that pushes back on you as you swim through the water or run through the air. Friction not only affects an athlete, but also the object they may be throwing, hitting, or kicking—like a baseball, a tennis ball, or a soccer ball.

Movement of any kind deals with physics of air flow, engineering design, and (unfortunately) sometimes collision. The verdict? Athletes need to know a LOT of science to do well in their sports.

​ Science is not just found in the activities themselves but also in the equipment they use and clothes they wear. Most of today’s superstar athletes rely on clothing and equipment enhanced with nanotechnology. What is nanotechnology? Nanotechnology is the science of the super small—microscopic even. One nanowire is 1,000 time thinner than a single strand of human hair. Now that is SMALL! Materials made with nanotechnology are stronger, more durable, and yet lighter and more flexible.

Nanotechnology produces swimsuits that allow the athlete to glide through the water faster, golf clubs that hit the ball farther, and tennis rackets that flex more easily to provide the hard smash across the net. This innovative new technology has already been used in the Olympics. In 2008, swimmers Michael Phelps and Natalie Coughlin wore swimsuits that were created with nanofibers. These nanofibers are woven tightly so that the swimmer’s bodies become more streamlined (like a shark!) allowing them to glide through the water faster. In the 2014 winter Olympics, the U.S. speed skaters wore specially created vented suits (like the swimsuits—to reduce drag), and in the 2018 winter Olympics, the USA Snowboarders will be wearing snow gear inspired by the space program.​ Nanotechnology is a cutting-edge science that is changing the world of sports—and in particular the Olympics— as we know it. Will you make nanotechnology part of your game?

TheLZR Raceris a line ofcompletion swimsuits manufactured by Speedo using a high-technology swimwear fabric. In March 2008, athletes wearing the LZR Racer broke 13 swimming world records. Much like other suits used for high competition racing, LZR Racers allow for betteroxygen flow to the muscles, and hold the body in a more hydrodynamic position, while repelling water and increasing flexibility. Kathy Barnstorff via Wikimedia Commons

Serena Williams uses a nanotech racket and Phil Mickelson uses nanotech technology in his game. Seems to be going well for both of them. (l) Wikimedia Commons (R) Photo by Siyi Chen via Wikimedia Commons

​A graphic highlighting all of the ways nanotechnology enhances the effectiveness of sports equipment. Nanowerk viaWikimedia

​You would have to increase a carbon nanotube x100,000 to make it the size of a strand of hair.​NIEH.gov

​Want to know more? Jennifer Swanson's Super Gear: Nanotechnology and Sports Team Up was listed as one of the 2016 Best STEM Books by the National Science Teachers Association.​Colorfully illustrated by photos, this book introduces "the science of the very small" as applied to sports equipment and clothing.

*NEWSFLASH*September, 2018: iNK begins its fifth year of publication of the Nonfiction Minute-- an amazing free resource with more than 4 million page views.

*NEWSFLASH *The NCSS-CBC Notable Social Studies Committee is pleased to inform youthat 30 People Who Changed the World has been selected for Notable Social Studies Trade Books for Young People 2018, a cooperative project of the National Council for the Social Studies (NCSS) & the Children’s Book Council